Human Anatomy Unit 4

Circulatory system, respiratory system, digestive system, and urinary system

Arteries

• vessels that carry blood away from the heart

• blood usually contains nutrients and oxygen, but isn’t always oxygen-rich

Capillaries

• smallest vessels which run through all the tissues of the body

• internal respiration - gas exchange

• oxygen and nutrients exit from the capillary beds and into the tissues

• metabolic wastes (CO2) are transported from tissues into capillary beds

• connect arterioles to venules

• only have one layer of endothelium

Arterial

• the heart pumps blood through progressively smaller vessels

• oxygen-rich

Venous

blood travels through vessels that get progressively larger while traveling to the heart

Veins

• vessels that carry blood to the right side of the heart

• oxygen-poor blood and increased waste

• where the majority of blood is distributed

• contain valves that are made when the tunica interna invades the lumen → prevent blood from flowing backwards

Systemic circulation

includes all the arteries leaving the heart, going to the capillary beds where internal respiration occurs, and the veins returning blood to the heart

Anemia

lower than normal (<45%) hematocrit

Polycythemia

• higher than normal (>45%) hematocrit

• results in clumping and blockage of pathways that obstruct blood flow to the tissues

Blood smear

observing elements of blood smeared out on a microscope slide

Hematocrit

~45% of the blood made up of RBCs

Plasma

• mostly made up of water that transport organic molecules, inorganic molecules, and formed elements

• contains plasma proteins

Erythrocytes

• RBCs

• deliver O2 and remove CO2

• only survive about 4 months → constant turnover

• plasma membrane enclosing hemoglobin

• biconcave shape

Leukocytes

• WBCs

• defense against infection

Thrombocytes

• platelets

• fragments of megakaryocytes critical for clotting

• produced through thrombopoiesis

• works with fibrinogen (fibrin) to set up blood clots (thrombus) 

Erythropoiesis

• development of red blood cells, starting with a pluripotent hematopoietic stem cell in the red bone marrow

• produces erythrocytes or mature blood cells with no nuclei or organelles

• driven by the hormone erythropoietin (EPO)

Hemoglobin

each molecule within an RBC can bind with four oxygen molecules

Erythropoietin (EPO)

• hormone that stimulates erythropoiesis

• released by the kidneys

• also used in blood doping to increase the number of RBCs

Iron

• found in Heme groups of hemoglobin and able to bind to oxygen

• deficiency of this can also lead to anemia

Blood typing

• based on antigens on the surface of RBCs

• determined by genes

Antigen

• on surface of RBCs

• recognized by antibodies

• if not recognized by antibodies → immobilization (attack it)

• A, B, AB, O

Agglutinogen

antigen — A or B

Agglutinin

antibodies — anti A or anti B

Type A

• A antigens/agglutinogens

• Anti-B antibodies/agglutinins (Y)

• can’t receive from type B or AB

• can receive from type A and O

Type B

• B antigens/agglutinogens

• Anti-A antibody/agglutinins (Y)

• can’t receive from type A or AB

• can receive from type B or O

Type AB

• both A and B antigens/agglutinogens

• no anti-A or anti-B antibodies/agglutinins

• can receive from types A, B, AB, and O

• universal recipient

Type O

• no A or B antigens/agglutinogens

• Anti-A and Anti-B antibodies/agglutinins

• can’t receive from types A, B, and AB

• can receive from O

• universal donor

Rh factor

• positive if RBCs contain this, negative if they do not

• important for compatibility during pregnancy

Leukocytes

• part of the body’s immune defense system

• contains large, multi-lobe nuclei

• also begins as a hematopoietic stem cell, which then goes through leukopoiesis

• granular or agranular

Granular WBC’s

• eosinophils

• basophils

• neutrophils

Agranular WBCs

• monocytes

• B lymphocytes

• T lymphocytes

WBC order of abundance (from highest to lowest)

• neutrophils

• lymphocytes

• monocytes

• eosinophils

• basophils

CBC

• complete blood count

• includes hematocrit, hemoglobin count, WBC count

• Differential (“Diff”) - distribution of WBC categories

Leukemia

• cancer involving leukopoiesis

• non-immunocompetent WBCs take up space, resources, and nutrients

Embolus

when a blood clot travels

Plasma proteins

• manufactured in the liver

• Albumin, globulin, and fibrinogen

Fibrinogen

plasma protein that works with platelets to help with clotting

Mediastinum

• middle section of the ventral body cavity where the heart is located

• heart deviates to the left side

Apex

at the bottom of the heart and lives in the fifth intercostal space in the midclavicular line

Base

widest portion of the heart

Pulmonary circuit

pumps blood to the lungs to pick up oxygen and then bring oxygenated blood back to the heart

Systemic circuit

pumps oxygenated blood to all the cells and tissues of the body and then brings deoxygenated blood back to the heart

Whole blood donation

most commonly used for trauma, surgery, and hemorrhage

Plasma donation

most commonly used for burn injuries, immune therapies, and clotting factor deficiency

Endocardium

innermost layer of the heart wall that’s made up of simple squamous epithelium

Myocardium

• thicker, middle layer of the heart wall that’s made up of cardiac muscle

• must be depolarized first before it can contract

Epicardium

• outermost layer of the heart wall that’s made up of connective tissue

• same as visceral pericardium

Systole

when the myocardium contracts

Diastole

when the myocardium relaxes after contracting

Visceral pericardium

• inner layer of the pericardium that’s in contact with the heart

• same as epicardium 

Parietal pericardium

outer layer of the pericardium

Pericardial cavity

space between the visceral and parietal pericardium that’s filled with pericardial fluid

Pericardium

sac in which the heart lives

Fibrous pericardium

• thicker layer of pericardium outside of the visceral layer

• anchors the heart within the mediastinum to the diaphragm

Cardiac tamponade

• excess fluid within the pericardial sac that inhibits the efficiency of the heart contracting

• pericardial synthesis - insert a needle into the space and withdraw excess fluid

Anterior view of the heart

• look for two major vessels

• can only see the right atrium, right ventricle, and a little bit of the left ventricle

Posterior view of the heart

• identified by four pulmonary veins

• able to see the left ventricle and this is the only way to see the left atrium

Papillary muscles

• only found in the ventricles

• act as an anchor for the chordae tendinae

Chordae tendinae

• attached to the AV valves and then anchored to the papillary muscles

• pressure from the atria opens and closes the valves

Opening of the AV valves

caused by pressure from the atria

Lub

sound able to be heard when the AV valves close which is caused by the build up of pressure in the atria

Dub

sound able to be heard when the semilunar valves close

Right atrium

• fed into by the superior vena cava, coronary sinus, and inferior vena cava and then pumps blood to the right ventricle

• contains pectinate muscles and the fossa ovalis

Pectinate muscles

internal ridges of myocardium in the right atrium

Fossa ovalis

depression in wall of right atrium that marks the former location of the foramen ovale

Right/left ventricles

• pumping chambers that receive blood from the atria through the AV valves

• contain trabeculae carnae, papillary muscles, and the chordae tendinae

Trabeculae carneae

internal ridges in the ventricles that keep the walls from clinging to each other during contraction

Papillary muscles

• only found in the ventricles

• act as an anchor for the chordae tendinae

• contract and tug on chordae tendinae

• don’t help valves open

Chordae tendinae

• attached to the AV valves and then anchored to the papillary muscles

• prevent valves from prolapsing during ventricular systole

• pressure from the atria opens and closes the valves

Left atrium

• mostly on the posterior side of the heart

• auricle - earlike flap that can be seen on the left side of the heart from the anterior view

• fed into by four pulmonary veins carrying oxygenated blood from the lungs

Right atrioventricular (AV) valve

• tricuspid

• what blood travels through to go from the atrium to the ventricle

Left atrioventricular (AV) valve

• bicuspid

• what blood travels through to go from the atrium to the ventricle

Aortic valve

• semilunar valve

• blood passes from the left ventricle through this valve to the aorta

• openings to right and left coronary arteries (coronary circulation)

Pulmonary valve

• semilunar valve

• controls the opening from the right ventricle to the pulmonary trunk

Right and left coronary arteries

• arises from the aortic valve

• have branches that supply the heart

Coronary sinus

• where venous, deoxygenated blood collects

• located on the posterior side of the heart

• blood taken to the right atrium from here

• blood brought here by cardiac veins

Cardiac conduction system

• made up of cells that generate and conduct electrical signals

• built into the myocardium

• fires 70 times per minute (heart rate)

Sinoatrial (SA) node

• bundle of electrical tissue buried in the myocardium of the right atrium that fires its electricity and sends it to the AV node

• also called the “pacemaker of the heart”

Atrioventricular (AV) node

• bundle of electrical tissue buried in the myocardium near the tricuspid valve

• the electric signal traveling from the SA node to this depolarizes both atria and results in the contraction of the myocardium (systole)

• the impulse pauses for a second before traveling to the AV bundle

AV bundle

• electrical impulse travels from the AV node to here

• located in the right ventricle

• sends impulse to the right and left bundle branches

Bundle branches

• located along the interventricular septum

• spread the electrical impulse to the ventricles

Purkinje fibers

• branch from the right and left bundle branches

• depolarize both ventricles, leading to contraction

• located at the bottom of each ventricle

Sinus rhythm

normal rhythm/heart rate

Arrhythmia

• deviation from normal sinus rhythm

• can be caused by the nervous system, medications, or other influences on the SA node

• tachycardia or bradycardia

Tachycardia

• increase in normal heart rate

• sympathetic nervous system

• adrenaline

Bradycardia

• decrease in normal heart rate

• parasympathetic nervous system

• acetylcholine

EKG

• electrical monitoring of the cardiac conduction system

• P wave, QRS wave, and T wave

P wave

• first wave of an EKG

• corresponds with atrial depolarization

QRS wave

• corresponds with ventricular depolarization

• atrial repolarization is also happening here

T wave

ventricular repolarization

Tunica interna (endothelium)

inner layer of blood vessels that’s made up of simple squamous epithelium

Tunica media

• middle layer of blood vessels that’s made up of smooth muscle

• controlled by the autonomic nervous system

Vasoconstriction

when the tunica media contracts and decreases the diameter of the lumen, resulting in more resistance and higher blood pressure

Tunica externa

outer layer of blood vessels made up of connective tissue

Valves

allow one way flow of blood

Arteriole

contains a sphincter that vasoconstricts to control the amount of blood that can enter a capillary bed

Arterial systemic circulation of the upper limbs

1. aortic arch

2. brachiocephalic trunk (R)

3. subclavian artery

4. axillary artery

5. brachial artery

6. radial/ulnar arteries

7. palmar arches

Arterial systemic circulation of the lower limbs

1. aortic arch

2. abdominal aorta

3. common iliac arteries

4. external iliac artery

5. femoral artery

6. popliteal artery

7. anterior and posterior tibial arteries

8. dorsal pedal artery

Venous systemic circulation of the upper limbs

1. radial/ulnar veins

2. brachial vein

3. axillary vein

4. subclavian vein + internal jugular vein

5. brachiocephalic vein

6. superior vena cava

Venous systemic circulation of the lower limbs

1. anterior and posterior tibial veins

2. popliteal vein

3. femoral vein

4. external iliac vein

5. common iliac vein

6. inferior vena cava